X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 20 Dec 2009 02:36:31 -0500 Message-ID: X-Original-Return-Path: Received: from imr-da05.mx.aol.com ([205.188.105.147] verified) by logan.com (CommuniGate Pro SMTP 5.3c3) with ESMTP id 4027745 for lml@lancaironline.net; Fri, 18 Dec 2009 11:38:41 -0500 Received-SPF: pass receiver=logan.com; client-ip=205.188.105.147; envelope-from=Sky2high@aol.com Received: from imo-ma01.mx.aol.com (imo-ma01.mx.aol.com [64.12.78.136]) by imr-da05.mx.aol.com (8.14.1/8.14.1) with ESMTP id nBIGc0G7006180 for ; Fri, 18 Dec 2009 11:38:00 -0500 Received: from Sky2high@aol.com by imo-ma01.mx.aol.com (mail_out_v42.5.) id q.cef.6a549974 (29672) for ; Fri, 18 Dec 2009 11:37:57 -0500 (EST) From: Sky2high@aol.com X-Original-Message-ID: X-Original-Date: Fri, 18 Dec 2009 11:39:12 EST Subject: Re: [LML] Prop and Glide considerations X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1261154352" X-Mailer: AOL 9.5 sub 155 X-Spam-Flag:NO X-AOL-SENDER: Sky2high@aol.com -------------------------------1261154352 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Bill, Thank God somebody actually tries this stuff (uh, somebody with your piloting skills). Perhaps you are using Marvel Mystery Oil to reduce engine friction.......... Is your MT prop electric? My understanding is that oil pressure managed props (non-feathering) would go to a flatter pitch as the pressure is diminished and the prop slows - perhaps the flatter pitch keeps the prop from actually stopping?. I think I only suggested that those with a fixed pitch prop try to stop it (yes, a dangerous maneuver). Of course there is no choice if the engine seized. I haven't flown a fixed pitch prop airplane since 1998. The fixed pitch prop Cozy MkIV flier I know said that there is a range for his airplane - a two bladed prop can be stopped at around 90+ Kts and will stay stopped until around 115+ Kts. Of course it comes to a stop with the blades horizontal in the wing wash (ah, pushers). He now has a three bladed prop and he doesn't know if it can be stopped. Let's try this then - CS fliers have an option of pitch control and should know the descent rate at best glide for the extremes. I would say that a stoppage from seizure would be some in between. Fixed pitch fliers (and others) should know the rotten descent rate they get with the prop in cruise pitch and windmilling and use that for rule of thumb range estimates. Uh, 1000 fpm at 5000 AGL = 5 minutes and at 120 KIAS that's 2 NM per minute - ergo <10 NM depending on the wind or about a 10 to 1 rate (distance to altitude). Here is where GPS ground speed is useful. In other words, at least know the worst case descent rate. Your final paragraph is "spot on" and there are many ways steepen the descent - wheels out, flaps down, prop to flat pitch and/or entering a slip. Oh yeah, a 300 series slow-speed flaps-out slip can lead to the nose bobbing up and down. As others have mentioned, gear up landings on a hard smooth surface don't need much "roll-out" - and note that it will turn away from the exhaust pipe side since the metal slides easier than glass (believe me, I know). Do what ya can to know your airplane... Scott In a message dated 12/18/2009 9:20:00 A.M. Central Standard Time, n5zq@verizon.net writes: Hiya Scott, Good info on glide ratios. You advocate stopping the prop. In most cases, this would produce slightly less drag than a windmilling, but high angle (prop control pulled back) prop. Problem is, I don't think that it can be done in our planes. I know for sure that I can't do it in our 320...I've tried. With the engine shut down and prop back I've slowed to just above a stall and the prop just keeps going. I've got an MT prop which will go to a higher angle than most others, maybe this is why. Has anybody been able to stop a prop (assuming no engine damage and a non-feathering prop in any kind of Lancair? My guess is that in an actual emergency, it would probably be best not to attempt it. Speaking for myself, I've got just so much concentration and the prop stopping maneuver would use up a bunch. When thinking about engine out procedures we always think about maximizing the glide. This is, of course, the proper thing to do to give you more time to think and plan. There are times, however when it is advantagious to MINIMIZE the glide ratio. Pushing in the still spinning prop will allow you to do this. When I was an examiner I conducted hundreds of private and commercial flight tests always including a simulated forced landing. Getting too high was just as common as a too low and the actual outcome would likely be worse. Having the ability to shove the prop forward gives you one more tool to modify your descent. That option is not available if the prop is stopped (the possible exception would be a feathering prop with an accumulator). I agree with Bill Kennedy. Learn how YOUR airplane glides and practice simulated forced landings. In our 320 with the engine at idle and the prop full aft I get a descent rate down of 500 fpm at 110 kts. With the engine SHUT DOWN it's 900 fpm. My suggestion would be to learn what your airplane does with the engine actually shut down, obviously at high altitude, good weather, and over an airport with a long runway. Once you have that number, you can do your engine out practice with the engine at idle and the prop adjusted to the RPM that gives you the same rate of descent that you discovered in your shut down test. Your practice then should give you very realistic glide performance. Bill Harrelson N5ZQ 320 1,750 hrs N6ZQ IV under construction -------------------------------1261154352 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
Bill,
 
Thank God somebody actually tries this stuff (uh, somebody with your= =20 piloting skills).  Perhaps you are using Marvel Mystery Oil to reduce= =20 engine friction..........
 
Is your MT prop electric?  My understanding is that oil pressure= =20 managed props (non-feathering) would go to a flatter pitch as th= e=20 pressure is diminished and the prop slows - perhaps the flatter=20 pitch keeps the prop from actually stopping?.
 
I think I only suggested that those with a fixed pitch prop try to st= op it=20 (yes, a dangerous maneuver).  Of course there is no choice if the eng= ine=20 seized.  I haven't flown a fixed pitch prop airplane since 1998. = ; The=20 fixed pitch prop Cozy MkIV flier I know said that there is a range for his= =20 airplane - a two bladed prop can be stopped at around 90+ Kts and will sta= y=20 stopped until around 115+ Kts.  Of course it comes to a stop with the= =20 blades horizontal in the wing wash (ah, pushers).  He now h= as a=20 three bladed prop and he doesn't know if it can be stopped.
 
Let's try this then - CS fliers have an option of pitch control and= should=20 know the descent rate at best glide for the extremes.  I would= say=20 that a stoppage from seizure would be some in between.  Fixed pitch= fliers=20 (and others) should know the rotten descent rate they get with t= he=20 prop in cruise pitch and windmilling and use that for rule of th= umb=20 range estimates.  Uh, 1000 fpm at 5000 AGL =3D 5 minutes and at 120= KIAS=20 that's 2 NM per minute - ergo <10 NM depending on the wind or about a= 10 to 1=20 rate (distance to altitude).  Here is where GPS ground speed is=20 useful.  In other words, at least know the worst case descent rate.
 
 Your final paragraph is "spot on" and there are many ways= =20 steepen the descent - wheels out, flaps down, prop to flat pitch and/= or=20 entering a slip.  Oh yeah, a 300 series slow-speed flaps-out sli= p can=20 lead to the nose bobbing up and down.  As others have mentioned,= gear=20 up landings on a hard smooth surface don't need much "roll-out" - and note= that=20 it will turn away from the exhaust pipe side since the metal sli= des=20 easier than glass (believe me, I know).
 
Do what ya can to know your airplane...
 
Scott
 
In a message dated 12/18/2009 9:20:00 A.M. Central Standard Time,=20 n5zq@verizon.net writes:
Hiya Scott,
 
Good info on glide ratios. You advocate stopping the prop. In most= cases,=20 this would produce slightly less drag than a windmilling, but high angle= (prop=20 control pulled back) prop. Problem is, I don't think that it can be done= in=20 our planes. I know for sure that I can't do it in our 320...I've tried.= With=20 the engine shut down and prop back I've slowed to just above a stall and= the=20 prop just keeps going. I've got an MT prop which will go to a higher ang= le=20 than most others, maybe this is why. Has anybody been able to stop a pro= p=20 (assuming no engine damage and a non-feathering prop in any kind of= =20 Lancair?
 
My guess is that in an actual emergency, it would probably be best= not to=20 attempt it. Speaking for myself, I've got just so much concentration and= the=20 prop stopping maneuver would use up a bunch. When thinking about engine= out=20 procedures we always think about maximizing the glide. This is, of cours= e, the=20 proper thing to do to give you more time to think and plan. There are ti= mes,=20 however when it is advantagious to MINIMIZE the glide ratio. Pushing in= the=20 still spinning prop will allow you to do this.
 
When I was an examiner I conducted hundreds of private and commerci= al=20 flight tests always including a simulated forced landing. =20 Getting too high was just as common as a too low and the= =20 actual outcome would likely be worse. Having the ability to shove= the=20 prop forward gives you one more tool to modify your descent. That= option=20 is not available if the prop is stopped (the possible exceptio= n=20 would be a feathering prop with an accumulator).
 
I agree with Bill Kennedy. Learn how YOUR airplane glides and= =20 practice simulated forced landings. In our 320 with the engine at idle= and the=20 prop full aft I get a descent rate down of 500 fpm at 110= kts.=20 With the engine SHUT DOWN it's 900 fpm. My suggestion would be= to=20 learn what your airplane does with the engine actually shut down, obviou= sly at=20 high altitude, good weather, and over an airport with a long runway. Onc= e you=20 have that number, you can do your engine out practice with the engine at= idle=20 and the prop adjusted to the RPM that gives you the same rate of descent= that=20 you discovered in your shut down test. Your practice then should give yo= u very=20 realistic glide performance.
 
Bill Harrelson
N5ZQ 320 1,750 hrs
N6ZQ  IV under=20 construction
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